As conventional refrigerant air conditioners, there has been an air conditioner in that refrigerant gas separated in a gas liquid separator arranged in an intermediate pressure portion between a condenser and an evaporator is injected into an intermediate pressure portion of a compressor so as to increase a heating capacity (see Patent Document 1, for example). Also, there is an air conditioner in that instead of providing the gas liquid separator, part of high-pressure refrigerant liquid is bypassed and reduced in pressure, which in tern is injected into a compressor after it is evaporated by exchanging heat with that of high-pressure refrigerant liquid so as to increase a heating capacity (see Patent Document 2, for example).
Also, there is an air conditioner in that a liquid receiver is provided in an intermediate pressure portion between a condenser and an evaporator, so that heat of the refrigerant in the liquid receiver is exchanged with heat of the refrigerant sucked by a compressor (see Patent Document 3, for example).
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-304714
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2000-274859
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2001-174091